The present invention relates generally to fluid heating, and specifically to heating of a fluid for the purpose of cleaning or de-icing an automobile window.
Various methods and devices are known in the art for providing a spray of heated water or other washing fluid onto the windows of a vehicle. The heated fluid is particularly advantageous in removing ice from the vehicle windshield in cold weather. This ice removal function requires that a driver of the vehicle wait while the fluid is heated, before the windshield can be de-iced. Methods and devices known in the art are impractical for this purpose, however, since they typically use heat or electricity generated by the vehicle engine itself to heat the fluid, requiring the driver to wait an unacceptably long time for the fluid to reach a suitable temperature.
Using the vehicle battery to heat the fluid, independent of the vehicle engine, is also problematic because of the large current draw required to heat a sufficient quantity of fluid to effectively de-ice the windshield. The battery cannot typically provide sufficient current to heat the vehicle""s entire reservoir of washing fluid in a reasonable amount of time. Although methods and devices have been suggested for heating the fluid on-line, as it is about to be sprayed on the windshield, the battery also cannot provide enough current to heat a spray of sufficient volume to a high enough temperature to achieve effective de-icing.
U.S. Pat. No. 5,509,606 describes a hot wash device for an automobile windshield, which includes a container into which washing fluid from a reservoir is pumped and in which the fluid is heated by an electrical heating element before it is sprayed onto the windshield. The container is insulated and includes a thermostat that is used to ensure that the temperature of the fluid does not exceed a predetermined maximum. The container is kept full, with heat applied as needed to bring the cold fluid pumped into the container up to the desired temperature.
U.S. Pat. No. 5,118,040 describes electric apparatus for washing window glass of a vehicle. An insulated container is positioned between a reservoir of cold washing fluid and spray outlets to the vehicle window, in a position lower than the reservoir so as to be kept full of fluid. When the vehicle ignition is turned on, an electric heater heats the fluid in the container and remains active while the vehicle is in use. There is no provision, however, for rapid start-up and heating to de-ice the vehicle window.
U.S. Pat. No. 4,090,668 describes a windshield washing and deicing system which includes a reservoir having a sealed container therein. A pump transfers washer fluid from the reservoir to the container and from the container to a plurality of nozzles. Heated engine coolant is passed through a conduit in the reservoir. Electrical resistance wire heats the fluid in the container whenever the temperature drops below a certain minunum. Solenoid valves direct the spray from the tank to the front or rear window of the vehicle, but there is no suggestion of using the valves for any other fluid control purposes.
U.S. Pat. No. 5,012,977 describes a vehicle window washer in which washer fluid in a reservoir is heated, and in which a pump for spraying the fluid on the vehicle window has a variable outlet pressure. The temperature of the fluid in the reservoir is sensed, and the pump outlet pressure is varied accordingly in an inverse manner with temperature of the washer fluid, so as to maintain a more consistent fluid deposit on the window, as the fluid viscosity changes with temperature.
U.S. Pat. No. 5,354,965 describes a system for electrically heating a volume of windshield cleaning fluid in a motor vehicle. A vessel is filled with the volume of fluid to be heated, using PTC thermistors or other electrical heating elements. A control circuit regulates the length of time that the fluid is heated, in accordance with a prevailing ambient temperature, before the fluid is sprayed on the windshield. The circuit also prevents operation of the fluid heating when the vehicle engine is not running.
It is an object of the present invention to provide improved apparatus and methods for cleaning or de-icing a vehicle window.
It is a further object of some aspects of the present invention to provide apparatus and methods that enable rapid start-up of de-icing of a vehicle window.
In preferred embodiments of the present invention, a vessel is provided for heating a washing fluid before the fluid is discharged toward a window of a vehicle. Before the fluid is introduced into the vessel, the vessel is preheated, preferably by passing an electrical current through a heating element in the vessel for about one minute or less. When preheating is completed, the fluid is allowed into the vessel and is rapidly heated by contact therewith, leading to an increase in pressure in the vessel due to vaporization of a portion of the fluid. The fluid is then discharged at a desired temperature and pressure so as to clean and/or de-ice the window.
Although the preheating of the vessel draws only a moderate electrical input from the vehicle battery, it enables a sufficient quantity of hot fluid to be generated for de-icing the window before starting the vehicle more rapidly than in any practical window cleaning system known in the art. Moreover, the pressure generated by vaporization of the fluid helps to clear ice or other blockages that may have formed in tubing or nozzles through which the fluid is sprayed onto the window. It is also noted that spraying the heated fluid on the window""s exterior surface effectively defogs its interior surface, as well.
In some preferred embodiments of the present invention, after an initial quantity of the fluid has been heated and discharged from the vessel, a further quantity is introduced into the vessel and immediately heated. Once the further quantity has reached a desired temperature, it too is discharged, preferably after a delay of several seconds. This process continues for repeated heat/discharge cycles, until the window has been completely cleaned and de-iced. Preferably, the heat/discharge cycles are timed in a sequence whose parameters, such as discharge duration and intervals between discharges, are varied in accordance with ambient temperatures of the vehicle and the unheated fluid.
It will be understood that the term xe2x80x9cvehiclexe2x80x9d as used in the context of the present patent application and in the claims can refer to any type of wheeled vehicle having windows, such as an automobile or truck, as well as to a boat or airplane. Furthermore, the term xe2x80x9cwindow,xe2x80x9d although typically referring to the windshield of a vehicle, can refer to any transparent surface, including side and rear windows and outer mirrors, as well as covers of headlights and the like. In addition, whenever the term xe2x80x9ccleaningxe2x80x9d is used in the present application and in the claims in reference to an action involving spraying heated fluid on a window, the term will be understood to comprehend de-icing, as well. Those skilled in the art will appreciated that the principles of the present invention may be adapted for cleaning and de-icing other surfaces, including internal windows and mirrors, for example, as well as for supplied heated water and fluid for other purposes.
There is therefore provided, in accordance with a preferred embodiment of the present invention, apparatus for cleaning a window of a vehicle, including:
a vessel, having an inlet through which a washing fluid is received from a reservoir and an outlet through which the fluid is discharged for cleaning the window; and
a heating element for heating the fluid in the vessel, which element preheats the vessel before the washing fluid is received therein, whereby at least an initial quantity of the fluid is rapidly heated and discharged from the vessel.
Preferably, the vessel is at least partly drained of fluid held therein before the element preheats the vessel, wherein the vessel includes a drain valve, actuated in cooperation with operation of the heating element, through which the vessel is at least partly drained. Preferably, the drain valve includes a one-way valve. Further preferably, the fluid drains into the reservoir, substantially irrespective of the height of the reservoir relative to the vessel.
Preferably, the apparatus includes a pump, which conveys the fluid from the reservoir to the vessel after the element preheats the vessel, wherein the pump and the reservoir are preferably part of a pre-existing window cleaning system in the vehicle, into which the vessel and heating element are retrofitted. Alternatively, the entire apparatus may be produced as an integral unit, including the pump. Preferably, the rapid heating of the initial quantity of the fluid causes the fluid to be discharged at a pressure substantially higher than a pressure generated by the pump at the inlet of the vessel.
Preferably, the apparatus includes one or more valves, which regulate passage of fluid through the vessel responsive to operation of the heating element, wherein the one or more valves open and close in cooperation with operation of the heating element. Preferably, the one or more valves include a solenoid valve or alternatively, a hydraulic, pneumatic or vacuum-operated valve. At least one of the one or more valves is preferably fixed to the inlet of the vessel or, alternatively or additionally, to the outlet of the vessel, wherein the at least one valve fixed to the outlet opens responsive to a pressure increase in the vessel, due to contact between the fluid and the preheated vessel.
In a preferred embodiment, the apparatus includes one or more temperature sensors, which generate signals responsive to an operating temperature of the apparatus, and a controller, which receives the signals and regulates discharge of the fluid from the vessel responsive thereto. Preferably, after the initial quantity of the fluid is discharged, one or more additional quantities of fluid are refilled into the vessel and discharged therefrom intermittently, responsive to the temperature signals, wherein the quantities are discharged when the temperature signals indicate that the temperature of the fluid in the vessel is above a predetermined threshold, and the discharge is interrupted when the temperature of the fluid falls below the threshold. Alternatively or additionally, the quantities are controlled according to a predetermined timing sequence, which is selected responsive to the temperature signals, and the temperature threshold may vary among the quantities in the sequence.
In another preferred embodiment, the controller analyzes the signals to detect a malfunction of the apparatus and interrupts operation of the heating element when the malfunction is detected.
Preferably, at least one of the one or more temperature sensors is inside the vessel. The at least one sensor is preferably substantially immersed in the fluid in the vessel. Alternatively, the at least one sensor is positioned so as to be substantially out of the fluid in the vessel while the heating element preheats the vessel. Preferably, operation of the heating element is interrupted when the temperature inside the vessel exceeds a predetermined maximum.
In a preferred embodiment, at least one of the one or more temperature sensors is fixed on an outer surface of the vessel. Additionally or alternatively, at least one of the one or more temperature sensors is fixed to the reservoir or on an outer surface of the vehicle, most preferably on an outer surface of the window to be cleaned, covered by an at least partially reflective cover, so as to substantially neutralize the effect of solar radiation thereon. Preferably, the fluid in the vessel is heated to a temperature which is varied responsive to the signals generated by the at least one sensor fixed on the outer surface of the vehicle, or otherwise responsive to a temperature outside the vehicle.
Preferably, the vessel includes an inner compartment communicating with the outlet, in which compartment the heating element is positioned, and an outer compartment, generally surrounding the inner compartment, communicating with the inlet. Preferably, the vessel includes an insulating outer envelope substantially surrounding the outer compartment and a all between the inner and outer compartments, which is preheated by the heating element. Alternatively, the outer compartment is surrounding by one or more additional fluid compartments, external thereto.
Preferably, the apparatus includes a pressure relief valve.
Further preferably, the apparatus includes a bypass line, bypassing the vessel, through which the fluid is conveyed to clean the window without heating the fluid, wherein when cleaning of the window is required while the element is preheating the vessel, the fluid is diverted through the bypass fine. Preferably, an operator of the vehicle selects whether the heating apparatus is to be actuated, such that when the apparatus is de-actuated, fluid is conveyed through the bypass. Further preferably, the apparatus automatically switches between conveying the fluid through the vessel and through the bypass, responsive to a heating cycle of the vessel. When fluid is not available from the vessel, unheated fluid is, preferably, automatically conveyed through the bypass line.
In a preferred embodiment, the apparatus includes a remote input device, which is actuated by a user of the vehicle to initiate preheating of the vessel before starting the vehicle.
Preferably, the heating element includes a resistive heating wire. Alternatively or additionally, the heating element conveys heat from a heat source in the vehicle to the fluid in the vessel.
There is also provided, in accordance with a preferred embodiment of the present invention, apparatus for cleaning a window of a vehicle, including:
a vessel, having an inlet through which a washing fluid is received from a reservoir and an outlet through which the fluid is discharged for cleaning the window;
a heating element for heating the fluid in the vessel;
a temperature sensor, which senses a temperature in the vessel; and
a valve for controlling flow of the fluid through the vessel, which intermittently releases quantities of the fluid through the outlet at a desired temperature, responsive to the temperature sensed by the sensor.
Preferably, a windshield wiper is activated intermittently to clean the window responsive to the intermittent release of the fluid.
Preferably, the apparatus includes a controller, which regulates the intermittent release of the fluid according to a given timing sequence, preferably a predetermined or programmable sequence, wherein the timing sequence is varied responsive to an ambient temperature in the vehicle or, alternatively or additionally, to a temperature of an outer surface of the window.
Preferably, an initial quantity of the fluid is released at a substantially higher pressure than subsequent quantities.
There is further provided, in accordance with a preferred embodiment of the present invention, a method for cleaning a window of a vehicle using a washing fluid, including:
preheating a vessel;
introducing a quantity of the fluid into the preheated vessel, whereby the temperature and pressure of the fluid are elevated; and
discharging the fluid onto the window at the elevated temperature and pressure.
Preferably, the vessel is drained of fluid before preheating the vessel.
Further preferably, introducing the fluid includes pumping the fluid into the vessel at a pump pressure, wherein the elevated pressure at which the fluid is discharged is substantially greater than the pump pressure.
In a preferred embodiment, the method includes measuring a temperature of the fluid, wherein discharging the fluid includes controlling the fluid discharge responsive to the temperature measurement. Additionally or alternatively, a temperature of an outer surface of the vehicle is measured, wherein discharging the fluid includes controlling the fluid discharge responsive to the temperature of the outer surface.
There is moreover provided, in accordance with a preferred embodiment of the present invention, a method for cleaning a window of a vehicle using a washing fluid, including repeating a plurality of times in sequence the steps of:
heating a quantity of the fluid;
monitoring a temperature of the quantity of the fluid; and
discharging the quantity when a predetermined condition on the heating of the fluid is satisfied.
Preferably, the predetermined condition is satisfied when the temperature of the quantity of the fluid reaches a selected level. Alternatively or additionally, the predetermined condition is satisfied when a predetermined period of time has elapsed since beginning the heating.
There is furthermore provided, in accordance with a preferred embodiment of the present invention, vehicle windshield de-icing apparatus including: a plurality of individual heating units; and a multi-jacketed housing wherein each jacket surrounds one of the heating units, the jackets being interconnected by fluid conduits, including an inlet and outlet port, the housing being connected at the inlet port to a windshield washer fluid source and at the outlet port to a windshield spray head, the heating units being operated to heat the washer fluid during flow to the windshield spray head, the heated sprayed fluid providing a windshield de-icing effect.
There is additionally provided, in accordance with a preferred embodiment of the present invention, an electrically powered windshield de-icing device for vehicles, including a heatable container for windshield washing fluid connectable between a washing fluid reservoir and a spray heads opposite the windshield, and provided with an inlet port and an outlet port for the fluid, and having an electric heater element disposed inside the heatable container, the remaining liquid capacity of the heatable container not exceeding 300 ml, the heater element being connectable to the vehicle battery and being sized to heat the fluid contained in the heatable container to de-icing temperature within no more than one minute of actuation.